1. Field of the Invention
The present invention relates to a coating-developing system having a transporting device for transporting substrates to be processed, for example, semiconductor wafers, and a plurality of processing units arranged around the transporting device for subjecting the substrates to a coating process, a developing process, and processes preliminary to and subsequent to these processes.
2. Discussion of the Background
In the process of manufacturing semiconductor devices, for example, a series of processes is performed wherein a substrate to be processed, for example, a semiconductor wafer, is applied with a processing liquid such as a photoresist liquid and a photoresist film thus formed is exposed, for example, to light of reduced circuit pattern by a photolithography technique and then developed. This series of processes is very important for integration of semiconductor devices.
The series of processes includes cleaning a semiconductor wafer in a cleaning unit, subjecting the wafer to a coating with an adhesion promoter in an adhesion unit, then cooling the wafer in a cooling unit, and forming a photoresist film, that is, a photosensitive film, in a resist coating unit. Then, after the photoresist film is heated for baking (prebaking) in a heating unit, the semiconductor wafer is exposed to a predetermined pattern of light in an exposure unit, then applied with a developer in a developing unit to form the predetermined pattern thereon, and subjected to a baking process (postbaking process) to enhance the thermal modification for polymerization as well as the adhesion between the semiconductor wafer and the pattern.
As a system for performing such coating and developing processes, a coating-developing system is known in which various processing units mentioned above are vertically arranged one upon another around a transportation path extending in the vertical direction and semiconductor wafers are transported to and from the individual processing units by a transfer mechanism vertically movable along the transportation path (cf. U.S. Pat. No. 5,664,254).
In this type of system, the cleaning unit, the adhesion unit, the baking unit, etc. are placed one upon another to form one processing section, and the resist coating unit and the developing unit are placed one upon the other to form another processing section.
In the aforementioned coating and developing processes, the surface of a semiconductor wafer is subjected to the adhesion process before a resist liquid is applied to the surface of the semiconductor wafer, as described above, and an amine solvent is used in the adhesion process, with the result that alkaline components such as amines are produced. An amine solvent is also used as a solvent for an anti-reflection coating film which is a coating used in the exposure process to prevent abnormal exposure, similarly producing alkaline components such as amines.
If, in the above-described type of coating-developing system, alkaline components such as amines are produced in the adhesion process or the coating process, they may possibly flow into the developing unit because the resist coating unit and the developing unit constituting one processing section are placed one upon the other.
Where highly integrated devices are to be manufactured, such alkaline components flowing into the developing unit make it difficult to form circuit patterns with accurate line widths during the developing process, possibly lowering the yield of IC devices.